Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart2h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

3. Energy & Cell Processes

Enzyme Inhibition

Anatomy & Physiology

3. Energy & Cell Processes

Enzyme Inhibition

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Multiple Choice

Succinylcholine is structurally almost identical to acetylcholine. If succinylcholine is added to a mixture that contains acetylcholine and the enzyme that hydrolyzes acetylcholine (but not succinylcholine), the rate of acetylcholine hydrolysis is decreased. Subsequent addition of more acetylcholine restores the original rate of acetylcholine hydrolysis. Which of the following correctly explains this observation?

Succinylcholine must be an allosteric regulator for this enzyme.

The active site must have the wrong configuration to permit succinylcholine binding.

Succinylcholine must be a noncompetitive inhibitor.

The presence of succinylcholine changes the conditions in the solution, resulting in a denaturation of the enzyme.

Succinylcholine must be a competitive inhibitor with acetylcholine.

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Verified step by step guidance

Begin by understanding the concept of enzyme inhibition. Enzyme inhibitors can be competitive, noncompetitive, or allosteric, each affecting the enzyme's activity differently.

Recognize that competitive inhibitors resemble the substrate and compete for binding at the enzyme's active site. In this case, succinylcholine is structurally similar to acetylcholine, suggesting it competes for the same active site.

Consider the scenario: succinylcholine is added to a mixture containing acetylcholine and its hydrolyzing enzyme. The rate of acetylcholine hydrolysis decreases, indicating that succinylcholine is occupying the active site, preventing acetylcholine from binding.

Note that when more acetylcholine is added, the original rate of hydrolysis is restored. This implies that acetylcholine can outcompete succinylcholine for the active site when its concentration is increased, a hallmark of competitive inhibition.

Conclude that succinylcholine acts as a competitive inhibitor because it competes with acetylcholine for the enzyme's active site, temporarily reducing the rate of acetylcholine hydrolysis until more acetylcholine is added.